Boat



Sept. 8. 1925. 1,553,160

} w. A. HICKMAN BOAT Fii d Sept. 25, 1924 1320022202":wiiz'ame/ifiz'ekfiiam,

Patented Sept. 8, 1925.

UNITED STATES PATENT OFFICE.

Boar.

Application filed September To all whom it may 'corwem:

Be it known that I, WILLIAM ALBnR'r' HICKMAN, a subject of the King ofGreat Britain, and a resident of New London, county of New London, Stateof Connecticut, have invented an Improvement in Boats, of which thefollowing description, in con nection with the accompanying drawings, isa specification, like characters on the drawings representing likeparts. I

. This invention relates to boats and more particularly to thepropulsive systems thereof and the objectis to provide an improved andmore efficient method of pro elling ves-' sels. The invention will bereadily understood in view of the following description taken inconnection with the accompanying drawings wherein:

Fig. 1 is a plan view of a boat shown for illustrative purposesexemplifying a form of the invention;

Fig. 2 is a quasi-diagrammatic view illustrating in side elevation thestern portion of the boat shown in Fig. 1; 7

Figs. 3 and 4 are similar views;

Fig. 5 is a stern elevation of the boat shown in Fig. 4; and

i Fig. 6 is a diagram to be referred to.

The system of boat propulsion herein described involves the use of aso-called surface or semi-submerged propeller wherein the shaft bearinand supporting struts and preferably a so the less efficient innermostportions of the blades are disposed above the surface. of the water inwhich the boat travels; This is usually effected by providp ing. apropeller on a shaft disposed arallel to and above the normal water linew en the boat is at speed, the blades of the propeller dipping into thewater below the shaft as the shaft revolves. Such an arrangement of apropeller utilizing the direct propulsive eflect of the useful drivingportions ofthe propeller blades, say the outermost twothirds of thelengt of the blades, and eliminating the retarding force of drivingthrough the water those submerged parts which in the ordinary submergedscrew propeller system are necesary for carrying the useful parts of theblades, to wit, the innermost; thirds of the blades, the hub of thepropeller, the propeller shaft, bearings and struts, has demonstratedhigh. propulsive efficiency in boats ofwidely. varying t pes andparticularly in boats running at hlgh 25,1924. Serial No. 739,837.

speed and, when driven by an engine of mechanism organized adjacent thecenter of the propeller which would cause retardation were not present,but such a construction is obviously an impossible abstraction. In theaccompanying drawings I have illustrated b way of example merely a typeof boat simi ar' to that shown in my Patent No. 1,204,355, dated Nov. 7,1916, but not, however, because the scope of the invention is limited tothat typeof hull. Onthe contrary, it is applicable to hulls of widelydiffering t pes and to relatively slow boats or boats 0 largedisplacement as will appear as the description proceeds. 4

Referring to-these drawings I have therein illustrated a boat having ahull 7 provided with an inverted V-shaped bottom, the V graduallyflattening from forward to aft an merging adjacent the stern transom 11in a flat or substantiall flat transom bot-- tom 13. The boat is a aptedto be driven by a surface propeller 15 arranged on a proeller shaft 17extending substantially parallel with the normal water line of the boat,this being the most efiicientangle for driving" the boat forwardly throuh the water as will be well "understood. (gbviously for constructionalreasons, theshaft 17 is a certain distance above the bottom 13 of thestern transom and, if the propeller 15 were hung directly aft of thetransom 11, only theoutermost portions of the blades would dip below thelevel of the bottom edge 13 thereof. i

A s eed boat of the type illustrated when travel ing tends gradually torise toward the surface of the water as the speed increases owing to thestructure of. the under-bpdy and at high speed there will be but sllghtdis flac'ement by the hull andthe shaft 17 wi be raised correspondinglyabove the sur when the boat is at rest or moving at a moderate rate ofspeed. The water will flow out beneath the transom 11 leaving the bottomedge 13 thereof at a point considerably below 5 the normal level andcurve upwardly toward and above the normal surface forming a wave asillustrated more or less diagrammatically by either of the lines L and Hin- Fig. 2. The straight or relatively straight edge out the sterntransom 11 is an example of a surface of a boats hull which delivers afta sheet of water rising rearwardly in the form pf a wave.

The locatioribi the crest of the wave with respect to the transom 11will vary in ac cordance with the speed of the boat and the height ofthe wave will vary in accordance with the boats displacement, the heightof said wave as well. as the distance'of its crest from the transombeing due to the inertia of the water. The form of the wave issusceptible of accurate calculation for any conditions. its height willvary ed 3nd practically fired for For example, the boat an hour, thewater F cove the bottom line inches there inches one a h. inertia of thethis height speed the in Figs. 2 and l have illustrated without anyattempt dimensional accuracy a curve marked L representing the surfaceof ve this level. The i or course, regulate entirely upon the ill thewater when the boat is running at a relatively low speed and a curvemarked H representing the surface of the water when the boat is movingat a relatively high speed.

It will be obvious that if the propeller were hun directly aft of thetransom 11 in Fig. 2 e total elfective area of the blades when the boatis in motion would be small because the shaft 17 is necessarily higherthan the bottom line 13 of the transom and the propeller cuts the wavewhich is develo ed substantially at its trough. In ac-' cor ance with,my invention, therefore, the shaft 17 is so extended that the propeller15 is hungat a substantial distance aft fromthe transom 11- of the boatto..-i ntersect the trough and in the vicinity of its crest so that themajor portion of the effective surface of the propeller blade will cutthrough the water. Thus in Fig. 2 the propeller is shownjs so hung as todip substantially cally decreased'by the dropping astern of the crest ofthe wave.

ln application to boats of very high speed this automatic regulation ofthe dip of the propeller may be of considerable advantage. In thisinstance the propeller may be placed very far behind the line 13, forinstance,

six or seven feet, the crest of the wave in such coat being far astern.The surtace propeller intersecting this wave remote from its trough willhave suihcient submerged area to permit the boat to be driven againstits high resistance at a low speed while at eecis, when the resistanceor the is low, of the propeller blade engaging tie water will be theminimum amount to drive the boat having in view the very relativeinertias of the water at such speeds.

however, it were desired to provide 7* which would dip comparatively if"relatively high speed other (is, the wave close to its as shown. 1 3., yL siracle mor particularly in boats mod" Bi-114.1% speed or relativelygreat displacement, it will he seen from. inspection of 3 that thismight submerg the of the proin the wave L generated at low speed and thesurface propeller would then not function as such and there would be agreat loss of eificiency at the low speeds'or when starting when theresistance of the boat'is greatest. To ermit the mounting of thepropeller in sue a position as shown in Fig. 3 and to avoidthisdifiiculty I may utilize the construction shown in Figs. 4: and 5where l have provided an extension from the planing surface of the boat19 extending aft from the line 13 which develops the rearwardly risingwave, which surface prevents the rising of this wave in the line of thepropeller shaft. Ateither side of the propeller shaft the surface 19 maymerge into buttock portions 21 upwardly directed to permit the rising ofthe wave laterally adjacent the outer or active portions of thepropeller blades. The

I ""19 is practically an extension aft of the otrising wave at a pointremote from its" art tom of theboat and in thecase of a planingboat'must be looked upon as a portion of the actual planing area of thebottom and,

rich would be,

boat inany suitable manner and herein are shown as planes supported bystruts 23 from the rear transom 11.

The operation of the construction shown in Figs. 4 and 5 will be readilyunderstood and the preceding discussion made clearer by reference to Fi6 illustrating diagrammatically a prope leras viewed from the rear. Ifline H represents the level of the water adjacent the lower edge of thetransom 11, it will be clear that the propeller acting closely adjacentthis transom the other portions of the propeller would dip into thewater a relatively small portion of the blade. Suppose, however, thepropeller to be hun further aft as shown in Fig. 3 and the hue 6-?) to.represent the height of water of wave H at the location of thepropeller. It is clear from the figure that a much greater portion'ofthe propeller blade acts on the water. Now if a line 0--c represents thehei ht of the wave L at the same position, the ab of the propeller wouldnormally be submerged with disadvantageous results. By virtue of theconstructionof parts 19 and 21 as herein described, the wave is, as itwere, divided and prevented from rising in the vicinity of the shaft andtakes substantially the form indicated by the line d-aL-d. It is thusdiverted from the hub and its bearings and which if submerge detract somuch from its efiiciency while the outer portions of the blades, as willbe clear from the diagrammatic figure, are operating in a depth of waterrising to the line 0-0. Thus, in the position of the figure two bladesare simultaneously efi'ective, whereas a single blade would be operatinif the height of water were at the level -b. As applied moreparticularly to boats of medium speed the arrangements described permitthe use of surface propellers of re ativel .small diameter whichnevertheless wil have the same or even greater absolute areasubmergedthan larger propellers mountedin the conventional position.This will permit engines of a given piston displacement to runefficiently at a higher number of revolutions per minute in hulls of agiven weightand resistance. J f I have described certain specific applcations of the principles of my invention whereby the same ma be putinto practice.

7 formed to deliver aft a sheet 'of water rising;

It will be understoo thatthese exemplifications are for illustrativepurposes only,

the scope of the invention being defined by the following claims.

Claims-- 1. A high speed motor boat having a hull as a wave governed bythe inertia of the water and a surface or semi-submerged progllsr hungat such substantial distance aft m'said surface as to cut the waveremote spond with the increase in the relative inertia of the water atincreased speeds.

2. A motor boat having a surface or semisubmerged pro eller, a hullhaving a surface forward of said propeller to develop a rearwardlyrising wave, said propeller being hung aft of said surface to engagesaid wave, at a determined speed of the boat, at a substantial distancefrom the trough of said wave to permit maximum submergence of theeffective portion of the blades. 4 l

3. A motor boat having a hullprovided with a surface to deliver a sheetof water aft rising as a wave governed'by the inertia of the water, apropeller. hung relatively far aft of said surface with its hubsubstantially at the same depth and means to prevent the rising of thewave in suchmanner as to submerge said hub while permitting such risingat the blades.

4. A motor boat having a surface or semi submerged propeller and havingsurfaces incorporated with the hull of the boat which are so shaped asto deliver rearwardly sep arated waves directed to the blades of thepropeller away from the hub thereof.

5. .A boat having a hull having a bottom portion, a surface propellerhung aft of said bottom portion, a surface forward of said propeller todevelop a flow of water and buttocks for guiding said fiow from saidsurface to the outer portions of the propeller blades.

6. A motor boat having a surface or semisubmerged propeller, a surfaceforward of said propeller to develop a wave rising rearwardly, saidsurface being continued aft along the center line of the propeller toprevent rising of the wave to submerge the hub thereof.

7. A motor boat having a surface propeller hung aft thereof at asubstantial distance to engage the rising wave left astern by the boatas it advances at a point where its height substantially varies onchanges of speed of the boat, whereby a decreasing dip is procured asthe speed of the boat increases. r

8. In a motor boat, a surface propeller dis osed at a distance astern ofsaid boat an having a maximum dip at a point substantially coincidentwith the crest of a wave produced by the inertia of a stream of waterowing from beneath the boatwhen the latter istravelling at a givenspeed, said dip being automatically decreased as the speed of the boatincreases and thecrest of said wave is moved astern by inertia of thewater.

-9. A motorboatbomprising a hull, a sur'-" face propeller arranged at asubstantial distance astern of said hull to effect a maximum submersionof said propeller at a given speed of the boat and means to direct thestream of water flowing aft from said hull into engagement with the moreeffective propulsive portions of said propeller.

10. A motor boat comprising a hull having a transom stern, and a surfacepropeller arranged aft of said transom in substantial spaced relationthereto, the blades of said propeller having a maximum degree ofsubmersion when the boat is moving at a predetermined moderate speed anda vminimum degree of submersion when moving at top speed.

11. In a motor boat, a hull having a transom stern, and a surfacepropeller disposed aft of said transom substantially coincident with thecrest of a wave produced by the boat when traveling at a given speed.

12. in a motor boat, a hull having a transom stern, a surface propellerarranged aft and in selected spaced relation to said transom and meansto guide the stream of water flowing from beneath said transom to thepropulsive areas of the blades of said proeller. p in a meter boat, ahull having a transom stern, a surface ropeller arranged aft and inselected space relation to said transom and means constituting acontinuation of the bottom of said hull adapted to guide the stream ofwater from beneath said hull to the more effective propulsive areas ofsaid propeller.

14. In a motor boat, a hull having a transom stern, asurface ropellerarranged aft and in selected spaced som and means constituting acontinuation of the planing surface of said hull adapted to direct thestream of water flowing from beneath said hull to effective portions ofthe blades of said propeller, cutting said blades at opposite sides ofthe axis of said pro eller and in a plane substantiallyabove sai axis.

15. A motor boat having a surface propeller at the stern and arearwardly extending plate underlying the shaft and extending adjacentto the propeller to intercept and break the wave of Water flowing aftfrom the bottom of the boat whereb to divert it from the central portionof t re propeller.

16. A motor boat having a surface propeller at the stern thereof adaptedto en age the rising v1 ave of water in the wake of the boat and awater-break adjacent the shaft to divert the water from the centralportion of the propeller.

In testimony whereo t it have signed my name to this specification.

WELLEIAM fitEKiRT MQKMAPL relation to said tran-

